Normal-incidence optical modulators are attractive devices for optical fiber communications because they can be interfaced to optical fibers more easily than waveguide-based devices. They are also interesting for integration with high-complexity Silicon Complementary Metal Oxide Semiconductor (Si CMOS), because they promise the availability of large amounts of optical Input/Output (I/O) directly to Very Large Scale Integration (VLSI) chips. One example of such devices is described in the article by K. W Goossen et al., entitled."GaAS MQW Modulators Integrated with Silicon CMOS", IEEE Phot. Tech. Lett. 1995 Apr; v.7(4), pp.360-362.
However, there are technological hurdles to be overcome before such devices can be considered for use in lightwave communications applications. The first of these obstacles is the production of modulator devices which operate at the 1.55 micron wavelengths used in most modem telecommunication systems. This has recently been demonstrated by Cunningham, et. al. at the 1996 Conference on Lasers and Electro-optics. A second obstacle is to design a modulator that will function with a modest applied voltage, while still producing the high-contrast (10:1) desired in lightwave systems. Other obstacles relate to optical fiber packaging and engineering.
What is desired is a low cost modulator device which compatibly interfaces to optical fibers and which provides high-contrast levels switchable using modest applied voltages.